In particular, in a postal sorting machine having conveyor buckets, the mail items are conveyed by a bucket carousel above a plurality of storage bins constituting sorting outlets of the sorting machine, and are dropped from the buckets into the storage bins merely by opening the bottoms of the buckets, as shown in U.S. Pat. No. 5,290,025.
Patent Document U.S. Pat. No. 6,648,284 discloses a storage bin for storing mail items. That bin has a bottom constituted by a wall inclined between two diametrically opposite corners of the bin, thereby enabling the mail items to be stacked better in the bottom of the bin, and enabling the stack of mail items in the bottom of the bin to be held in position better than with a bottom that is horizontal or perpendicular to the side walls of the bin.
Unfortunately, with that arrangement, the mail items (in particular open items like magazines) tend to bounce back off a side wall of the bin before being jogged into alignment in the bottom of the bin. More particularly, a mail item dropped into that type of bin tends to turn before it is jogged against a side wall of the bin, which can be detrimental to the remainder of the process of automatically sorting the mail item. In addition, the stability of the stack, and thus how well it stays together, is guaranteed only for flat mail items that are homogeneous, even though current sorting machines are required to sort mail items that are heterogeneous, i.e. of widely differing sizes. In addition, the arrangement of the bin known from the above-described document does not make it possible for the stack of mail items to be extracted automatically from the storage bin, which can be necessary during unstacking operations at the inlet of the sorting machine.